Lecture 7: New toolkit input models: Garnet

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Lecture 7New toolkit input modelsGarnet
Amulet

• Brad Myers
• 05-830Advanced User Interface Software

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Overview

• Try to provide more support so input handling
  isn't so difficult
• Make easy things simple and complex things
  possible
• Based on the "Model-View-Controller" architecture
  from Smalltalk
• True separation of graphics (view) and input
  handling (controller)
• Also uses idea from FoleyWallace of identifying
  types of input handlers
• move
• grow
• rotate
• text edit
• gesture
• select (pick)

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Innovations

• Identifying primitive "Interactor" objects and
  correct parameterizations so most direct
  manipulation UIs can be constructed by re-using
  built-in objects.
• Only a few kinds of behaviors, and standard
  parameters
• Real separation between input and output handling
  
• Handles all input
• insides of widgets
• and for application programs
• First successful separation of View from
  Controller in Smalltalk MVC
• Integration of gestures with conventional
  interaction.
• Easier to code because substantial re-use
• Built-in support for multi-window dragging

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General idea

• Attach interactor objects to a set of graphical
  objects to handle their input.
• Graphical objects don't handle input
• No "event methods" in objects
• Instead, define invisible "Interactor" objects
  and attach them to graphics
• Interactors can operate on multiple objects
• Strategy pick the right type of Interactor,
  attach to the objects to be moved, fill in
  necessary slots of interactor
• Widgets use interactors internally
• Can have multiple interactors on an object (e.g.,
  different mouse buttons)
• Interactors directly set slots of objects using a
  standard protocol
• constraints can be used to map those slots into
  behaviors
• Details of input events and event processing is
  hidden
• Used first in Garnet, refined in Amulet.

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Full Documentation

• Full Amulet Manual
• http//www-2.cs.cmu.edu/afs/cs/project/amulet/amul
  et3/manual/Amulet_ManualTOC.doc.html
• Tutorial
• Interactors and Command Objects

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Types of Interactors

• Am_Choice_Interactor select one or more of a
  set of objects
• Am_One_Shot_Interactor - single action, like
  Choice
• Am_Move_Grow_Interactor move or grow objects
  with the mouse
• Am_New_Points_Interactor to create new objects
  by entering points while getting feedback "rubber
  band" objects
• Am_Text_Edit_Interactor mouse and keyboard edit
  of text
• Am_Gesture_Interactor interpret freehand gestures

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Parameters for all Interactors

• Set of objects to operate on
• To be active, Interactor must be attached to an
  object which is (recursively) attached to the
  screen
• Equivalent to visibility of graphical objects
• Unlike graphical objects which can only be added
  as parts of windows or groups, interactors can be
  added as parts of any object rect.Add_Part(my_in
  ter)
• Default operates on the object attached to
• But also common to operate on any member of a
  group.
• Controlled by the Am_Start_Where_Test slot, which
  should contain a method

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Example Start_Where_Test

• SP_Ship_Mover    Am_Move_Grow_Interactor.Create(
  "SP_Ship_Mover")    .Set (Am_START_WHEN,
  "LEFT_DOWN")    .Set (Am_START_WHERE_TEST,
  Am_Inter_In_Part)ship_group.Add_Part(SP_Ship_Mov
  er)

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More standard parameters

• Multiple groups
• interactor can span multiple windows
• start, stop and abort events
• single key, mousebutton, "any" mousebutton,
  modifiers, (shift, meta...), double click, click
  vs. drag, etc.
• active?
• priority levels

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Parameters for specific types of Interactors

• For buttons (Choice Interactors)
• how many objects to select set, toggle,
  list-toggle
• For move-grow
• interim feedback object (while the mouse moves)
• if missing then object itself is modified
• gridding
• move or grow
• where-attach
• center, n, ne, nw, w ... , where-hit
• flip if change sides
• minimum size

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Example

• Am_Object feedback_circle moving_circle.Create()
    .Set (Am_LINE_STYLE, Am_Dashed_Line)  .Set
  (Am_VISIBLE, false)my_win.Add_Part
  (feedback_circle)// The definition of the
  interactor Am_Object objs_grower
  Am_Move_Grow_Interactor.Create()  .Set
  (Am_START_WHERE_TEST, Am_Inter_In_Part)  .Set
  (Am_GROWING, true)   // grow instead of move  
  .Set (Am_FEEDBACK_OBJECT, feedback_circle)objs_g
  roup.Add_Part (objs_grower)

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Parameters for New_Point

• interim feedback object (while the mouse moves)
• gridding
• minimum size
• abort if too small

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Parameters for Text_Interactor

• editing translation table (to map keystrokes and
  mouse into editing functions)

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Parameters for Gesture_Interactor

• gesture recognizer table
• If missing, can use this to get freehand drawings

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Simple Example

• To make an object movable with the mouse
• Am_Object rect Am_Rectangle.Create()
  .Set(Am_LEFT, 40) .Set(Am_TOP, 50)
  .Set(Am_FILL_STYLE, Am_Red) .Add_Part(Am_Move_Grow
  _Interactor.Create())

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Standard Behavior
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Operation

• Interactors do 3 things
• modify objects directly
• set Am_VALUE slot of their command
• call the command's Am_DO_METHOD
• Can just have a constraint from an object or
  widget to the Am_VALUE of the widget
• Method to override for application-specific
  operations
• Fill in the UNDO_METHOD to support undo

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Operation Picture
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Choice Interactor

• Three ways to get the result
• Access the Am_INTERIM_SELECTED and Am_SELECTED
  slot of the object itself
• By default, sets the Am_INTERIM_SELECTED and
  Am_SELECTED slots of the affected objects
• Constraints that depend on these slots
• Access the Am_VALUE slot of the interactor
• Write a Am_DO_METHOD for the command object, and
  access the command object's Am_VALUE slot

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Example

• Am_Define_Style_Formula (line_from_selected)  
  if ((bool)self.Get(Am_INTERIM_SELECTED))return
  Am_Red  else if ((bool)self.Get(Am_SELECTED))re
  turn Am_Black  else return Am_BlueAm_Object
  my_prototype Am_Line.Create().Set(Am_LINE_STYL
  E, line_from_selected)my_group
  Am_Group.Create().Add_Part(Am_Choice_Interactor.C
  reate().Set(Am_START_WHERE_TEST,
  Am_Inter_In_Part)

• Now add instances of my_prototype to my_group
• Also collects a list of the selected objects in
  the Am_VALUE slot of the command object in the
  interactor

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Values

• Value of Command in Choice Interactor set to
  object selected
• Value of Command in button-type widgets set to
  Label of command, or Am_ID field of the command
• Remember, label can be a string or a graphical
  object

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Debugging Tracing

• Can turn on tracing and get print out of which
  Interactors run and what they do
• Options trace all, trace only setting of slots,
  trace a particular interactor, short trace (only
  which interactors run), etc.
• Inspector just toggles inspecting all or none
• Printout to console window

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Example

• ltgtltgtltgtltgtltgt LEFT_DOWN x180 y289
  time3114329169Enter GO for ltgrow_inter_in_handl
  e_185gt, state0...Checking start event against
  wanted LEFT_DOWN SUCCESSChecking start
  where..  SUCCESSltAm_Rectangle_650gtMove_Grow
  starting over ltAm_Rectangle_650gt translated
  coordinates 169,268Calculated attach point for
  non-line is Am_ATTACH_SObject
  ltgrow_inter_in_handle_185gt setting Am_VISIBLE of
  ltSel_Rect_Feedback_197gt to trueObject
  ltgrow_inter_in_handle_185gt setting
  objltSel_Rect_Feedback_197gt setting
  objltSel_Rect_Feedback_197gt LEFT90 TOP142
  WIDTH182 HEIGHT148ltgtltgtltgtltgtltgt LEFT_UP x179
  y326 time3114329838 drawonableAmulet Test
  Selection Widget(0x4015b848)Enter GO for
  ltgrow_inter_in_handle_185gt, state1...Checking
  abort event against wanted CONTROL_g
  FAILEDChecking running where.. 
  SUCCESSltwindowgtChecking stop event against
  wanted ANY_MOUSE_UP SUCCESSMove_Grow
  stopping over ltAm_Rectangle_650gtObject
  ltgrow_inter_in_handle_185gt setting Am_VISIBLE of
  ltSel_Rect_Feedback_197gt to falseObject
  ltgrow_inter_in_handle_185gt setting
  objltAm_Rectangle_650gt setting objltAm_Rectangle_6
  50gt LEFT79 TOP121 WIDTH182 HEIGHT185

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Advanced Feature Priorities

• If two interactors want to run, priorities used
  to determine which
• Am_PRIORITY slot contains a number. Default 1
• When running, 100 added to it
• Inspector interactors use 300.0
• If multiple with same priority, runs the one
  attached closer to the leaf

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Example
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Advanced Feature Using Slots of Interactors

• In addition to value set into Command, a number
  of slots are set into the Interactor itself,
  which might be useful.
• Can get the interactor as the Owner of the
  command passed to the DO_METHOD
• Am_START_OBJECT, Am_START_CHAR, Am_FIRST_X,
  Am_FIRST_Y, Am_WINDOW, Am_CURRENT_OBJECT

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Doing something with results Command Objects

• Each Interactor and Widget has a Command object
  as a part in the Am_COMMAND slot
• Instead of executing a callback function,
  interactors and widgets create a "Command Object"
  and execute its "Do" method
• Slots of command object
• DO_METHOD
• UNDO_METHOD
• REDO_METHOD (undo the undo)
• SELECTIVE_UNDO
• SELECTIVE_REPEAT and SELECTIVE_REPEAT_On_NEW
• HELP for "balloon" or status line
• LONG_HELP
• ACTIVE (enabled) -- usually contains a constraint
  
• VALUE, OLD_VALUE
• etc.
• Like Command Objects in MacApp, but hierarchical
• Customize by overriding default methods

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Handling Undo

• Add an undo-handler to the window
• Each command will be registered with the undo
  handler
• Built-in types of undo handlers
• One undo then redo, like Mac
• Infinite undo, one redo
• Selective undo mechanism
• Each DO method saves necessary information for
  undo in command object

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Selective Undo

• Implementing selective undo not much harder than
  regular undo
• Allocates a new command object and adds to top to
  history list
• Semantics is based on what the user would want
• Undo the operation in a new context means to set
  the object back to its previous value
• Enabled if object is still available
• Undo of create is delete
• Redo the operation means to set the value of the
  object again create a new object
• Also, redo on new object

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Original Interface
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Commands in Widgets

• Various kinds of button panels
• Take list of items in the Am_ITEMS slot as an
  Am_Value_List
• Contents of list can be strings, graphical
  objects, or instances of Am_Command
• If commands, then the Am_LABEL field is used, and
  the DO_METHOD of that command is called
• If not commands, then DO_METHOD of the top-level
  widget is called
• For menu_bar, Am_ITEMS slot of each top-level
  command contains Am_Value_List of the sub-commands

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Innovations

• Better reuse
• Many commands are in the library and are usually
  used without change
• Cut, Copy, Paste, Create-Object, Delete-object,
  To-Top, etc.
• Usually can be used without change
• Easier to customize when necessary
• Better modularization
• Hierarchical means each level only has to deal
  with its own actions
• New form of selective undo, repeat
• Includes undo/repeat of selections and scrolling
• Single place for enabling, help, label, etc.
• Can be computed by constraints
• Makes scripting easier
• End-User programming by demonstration
• Parameterization possible without help from
  application
• May help with CSCW
• Executing the command on multiple machines

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Scripting

• Added for CHI'98
• Not in standard release
• Select set of commands and specify that in a
  program
• Can parameterize actions
• Moving selection handles
• Forwards, backwards, left, right, up, down, in,
  out
• Search for object of a particular type or value
• Little or no change to application if it supports
  Selective Repeat

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Pictures for Scripting, 1
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Pictures for Scripting, 2
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Pictures for Scripting, 3